Telegraph switchboard switching system



Dec. 13, 1938. A. R. BONORDEN 2,139,799

TELEGRAPH SWITCHBO'ARD SWITCHI NG SYSTEM Filed Aug. 26, 1936 9Sheets-Sheet 1 4 1 A T TORNEV Dec. 13, 1938. A. R. BONORDEN TELEGRAPHSWITCHBOARD SWITCHING SYSTEM 9 Sheets-Sheet 2 Filed Aug. 26, ,-l95sZZZ-2::-

INVENTOR A. R. BONORDEN ATTORNEY c- 9 A. R. BONORDEN 2,139,799

TELEGRAPH SWITCHBOARD SWITCHING SYSTEM F led Aug. 26, 1936 9Sheets-Sheet 3 FIG. 3

//v l/E/VTOR B R BONORDEN DEC. 13, A R BoN QRDE| 2,139,799

TELEGRAPH SWITCHBOARD SWITCHING SYSTEM Filed Aug. 26, 1956. 9Sheets-Sheet ,4

FIG. 4-A

FIG. 4 #7615 FIG 6 INVENTOR By A. R. BONORDEN A T TORNEV c. 13, 19 38.A. R. BC DNORDEN 2,139,799

TELEGRAPH SWITCHBOARD SWITCHING SYSTEM Filed Aug. 26, 1936 Sheets-Sheet5 MARG/NA L llllllll ll um MA I? GINAL /a 640 INVENTOR By A. R. BONORDEN6 A 7' TOR/VEV Dee-13, 1938. R BQNORDEN 2,139,799

TELEGRAPH SWITGHBOARD SWITCHING SYSTE IM Filed Aug 26, 1956 9Sheets-Sheet 6 //v vE/vmR R. BONORDE N A Tram/5 Dec. 13, 1938. A, RBONORDEN 2,139,799

TELEGRAPH SWITCHBOARb SWITCHING SYSTEM Filed Aug. 26, 1936 9Sheets-Sheet 7 A/ 5 N TOR By A. R. BO/VQRDE/V A TTOR/VEV i 138. A. R.BONORDEN TELEGRAPH SWITCHBOARD SWITCHING SYSTEM Filed Aug. 26, l936 9Sheets-Shget 8 FIG. 8

W630 W31 82 v T R m M W A R; BQ/VORQEW By I A T TOR/V5) A. R. BONORDENDec. 13, 1938.

TELEGRAPH SWITCHBOARD SWITCHING SYSTEM Filed Aug. 26, 1936 9Sheets-Sheet 9 ATTORNEY //v l EN TOR A. R. BONORDEN FIG. .9

POST 2 I Patented Dec. 13, 1938 UNHEE TELEGRAPH SVVITCHBOARD- SWITCHINGSYSTEM Allen Rudolf Bonorden,

Telephone and to American Fanwood, N. 5., assigncr Telegraph Company, acorporation of New York Application August 26, 1936,8erial No. 98,055

7 Claims.

his invention relates to communication systems and more particularly tosupervising and maintaining private, or order, wire service overintercity communication trunk circuits between test board attendantslocated in different cities.

An object of the invention is to permit an attendant at a test board orswitchboard in one locality to be connected with any one of a pluralityof attendants at a test board or switchboard in a different locality.

It is essential in test best operation in communication systems forattendants at two different localities, having charge of a particularservice at their respective switchboards, to obtain direct communicationwith each other and consequently it is desirable to have an arrangementwhich will facilitate certain direct communications or permit of anincoming call being rapidly transferred to an attendant responsible fora particular service. Heretofore in both toll and telephone practice thetransfer of calls, received over certain trunks or line circuits, ispossible to a very limited extent, that is the facilities at presentpermit the transfer to one or at the most two points in the oflice.

According to the present invention, the facilities provide for eachposition or section in a line of test board to become a potentialtransfer point and in the larger of said oflices these facilities extendto arrangements for transferring a call to any one of a plurality ofpositions or sections. In other words an attendant at a multiple type ofswitchboard may upon receiving an incoming call over an intercitycommunication trunk circuit, transfer the incoming call signal to anyparticular one of a plurality of trunk lamps, each of which is locatedat a different position or section in the switchboard. The multiple typeof switchboard may comprise two or more sections, each section havingone or more operators or attendants positions.

A feature of the present invention is that it provides a more flexiblearrangement than heretofore known in that an incoming call signal may betransferred to a signal lamp at any one of even than twenty positions.

Another feature is that an incoming call sigmay be transferred to a lampat any one of plurality of switchboard positions and then againtransferred to another lamp at one of the other positions.

Still another feature is that the arrangement may provide by propercross-connections, for any trunk circuit'to have either a primary or asecondary answering appearance at any on the multiple type ofswitchboard.

Another feature is the provision of having a sequence circuit associatedwith the trunk circuits or the positional key-sets. 5

Another feature is the provision of recalling the attendant at a primaryposition after the signal has been transferred to another position andthe attendant at the latter position has failed to answer.

Another feature is the provision of a transfer key so that for nightoperation all signals of diiferent trunk circuits normally appearing atdifierent primary positions may be caused to appear at some one positionused as a night or light load position.

Description A more complete understanding of-the invention may beobtained from the accompanying drawings in Which Figures 1, 2 and 3,represent an arrangement of the invention, when interconnected inaccordance with the block diagram Fig. 1A, wherein figure 1 showstwo-way communication lines and associated line equipment, Fig. 2 asequence circuit and associated control circuit for transferring callsand Fig. 3 answering jacks and lamps, associated busy lamps and trunktransfer keys, cord circuits and position transfer keys, cord circuitsand position transfer keys with associated equipment.

Figs. 4, 5 and 6 represent another arrangement of the invention, wheninterconnected in accordance with the block diagram Fig. 4A, whereinFig. 4 shows two-way communication trunks and associated line equipment,Fig. 5 a control circuit for transferring calls and Fig. 6, answeringjacks and lamps, associated busy lamps and trunk transfer keys, cordcircuits, position ester keys with associated equipment and circuitrelays.

7, 8 and 9 represent still another ar rangement of the invention, wheninterconnected in accordance with the block diagram 1A, wherein Fig. 7shows two way communication trunks and associated line equipmentincluding a cros's bar switch and Fig. 8 shows answering jacks andlamps, busy lamps, position transfer keys, cord circuits and a controlcircuit consisting of a rotary stepping switch.

Fig. 9 is an alternative arrangement of Fig. 8, which uses a relay typecontrol circuit.

Figures 1, 2 and 3 Referring to Figs. 1, 2 and 3, Hill isaninterposition office trunk, which terminates in jacks 306, 353! thecircuit of trunk I is opened momentarily and 302 of positions 1, 2 and3, respectively. which causes the momentary release of line relayAssociated with each of these jacks are answer- Hi3. If the line is keptopen sufliciently long, re-

be provided at additional positions, not shown. releasing relay Hi5,which after an interval re- As shown in the drawings positions 1 and 3are leases and closes a circuit from ground on its cross-connected byconductors 260, so that the winding through its back contacts,momentarily associated answering lamps 303 and 3135 are operated leftcontacts of relay I06 and winding of gether similarly placed contacts ofall the switch into jack see before the attendant at position 3cordingly a secondary answering position. It is then relay H35 holdsoperated in a circuit from to be understood, however, that, by theproper battery through the winding of relay I06, opcross-connection, anyposition in the switchboard erated contacts of relay I05, Winding ofrelay line up may be arranged as either a primary or MS, right operatedfront contacts of relay I06,

In order to transfer incoming calls from one tion, relay Hi6 releasesand relay I01 does not position to another, trunk 39 is provided with aoperate. It is seen therefore that the line relay rotary type steppingswitch having a stepping il will respond only to an open interval ofmagnet 20!, which causes the brush arms 202 definite minimum duration,and not too short irand 2&5, respectively; Each terminal of bank 294other closely, thereby preventing false line sigis connected to aconductor leading to an answernals.

ing lamp at the respective positions whereby each When relay I07operated it connected battery, lamp may be selectively lighted asrequired. Each with its right outermost and middle contacts, to contactof bank 205 is connected to a conductor conductors I09 which arecross-connected by conto which ground is selectively connected by theductors 280 to conductors 3M and 3|5. Answeroperation of one of thepositional transfer keys, ing lamps 3G3 and 305 of positions 1 and 3,reas key 309, 3H or 3 of position 1. In effecting spectively, aresimultaneou y lighted. Relay transferred is identified by the key 399,3H3, 3! I, most contacts to conductor 3|6 thereby lighting etc. and. thetrunk is identified by the associated the busy lamps at all positions.Attendants at transfer key, such as key SL2. In order to use positions 1and 3 respond to the lighted lamps a transfer trunk common to allpositions, such as 393 and 355 with cord circuits 3!! and 3H). AstrunkSIS, the conductors of which connect tosuming that the attendant atposition 1 plugs which are arranged in a manner similar to the conductor328 and through the uppermost oprelays of an automatic listening,straightforward rated contacts of jack 3&9 to ground. Relay trunksytsem, which is well known in the tele- Hi l in operating disconnectsground with its in-. phone art. The aforesaid sequence circuit funcherright back contacts from conductor Ill', tions so that the transfertrunk 3| 3 is available thereby releasing relay I01 and extinguishing toonly one trunk a a t thereby ak n i the answering lamps 303 and 305. Theattendunnecessary to bring a separate conductor from a t at position 3,observing that lamp 305 is exe h k y to the on s of ank 203, and thetinguished knows that the call is being handled contacts of similarbanks associated with trunks t nother position and accordingly makes nolo! and 0 Another feature of the sequence further effort to answer thecall. Relay I01 in circuit is the arran m n wher y calls aw itreleasingalso disconnects battery with its right n th d s r p be o e given, partcula refwith its left innermost contacts, thereby main- "c5 e enee Was md to the trunk and its taining the lighted condition of the busy lampssociated apparatus. A similar description also t l positions. Relay I84in operating also pp to the othe trun s, I0 and "J A mo e closes throughwith its contacts H3 the lower mp understanding of the Operation of theconductor of trunk I60 to lower conductor of inVeIltion y be a d f om hefollowing trunk H4 and with contacts H2 disconnects the 79 detaileddescription. winding of relay Hi3. Contacts H3 are arranged Let it beassumed that an attendant at a disto make before contacts H2 break,thereby maintant point desires to communicate over trunk loll tainingWithout interruption the continuity of the with an attendant at thesecondary answering line. position, position 2 of Figure 3. To initiatea call When the plug of cord circuit 3" is inserted into jack. 3%, theattendant of position 1 is in telegraphic communication over the tip andsleeve conductors of jack 300, trunks H4 and I00 with the distantattendant. Assuming that, as before stated, that the call is to betransferred to the secondary position 2, the attendant of positioni'will upon being requested to effect the transfer, now operatesmomentarily the key 3l2 associated with jack 386, thereby closing acircuit for operating relay llll, which is traced from battery throughthe right contacts of relay H5, winding of relay 5 it, over conductor 32I, through contacts of key M2 and contacts 322 of jack 300 to ground.Relay H8 in operating looks through its left contacts to ground on theright inner front contacts of relay ic i and with its right middlecontacts closes a circuit from ground over conductor HE to battery 2H5through the winding of the sequence circuit relay 2111, which operates.If at this time no other trunkas I0! or lSZ-is being transferred by anattendant at another position, relays 209 and 2 are not operated andconsequently a circuit is closed for operating relay 238 associated inthe sequence circuit with relay 2%. This circuit may be traced fromground 238 on the back contacts of relay 213 through the winding ofrelay 2M, (which also operates for a purpose hereinafter explained),back contacts of relays 2H and 2 39, right front contacts of relay 2%!and winding of relay 298 to battery. If, however, another trunk at thistime is being transferred either relay 259 or 2H is operated and thecircuit before traced for operating relay 208 is open at the backcontacts of relay 269 or 2| I. If relay 209 is operated, its winding isconnected to battery 2l5 through the left break contacts of relay 208;if relay 2!! is operated then its winding is connected to battery 2 itthrough left break contacts of both relays 2M! and 208.

A general description of the operation of the sequencecircuit, which asbefore stated is used in the telephone art for straightforward trunkingwill now be given. Relay 2! I may be said to' be in the first, relay 2stin an intermediate and relay Zii'i in the last or highest numberedposition in the sequence circuit chain. If relays 2G9 and Eli; areoperated, and lines are awaiting service in the last and firstpositions, relay 291 is operated, but relay 2H is not operated, sinceits operating path is disconnected by the left inner break contacts ofrelay 2H3. When relay 299 releases conductor 2% is transferred from thewinding of relay Ziil to conductor 239 by the continuity contacts ofrelay 209, thereby holding relay 2M operated through the right makecontacts of relay 2l3'i and the winding of relay 298, which nowoperates. Relay 2 does not operate since its circuit is opened by theleft inner break contacts of relay 288. When relay 2B! releases,releasing relay 2%, the circuit through relay 2H! is opened and thisrelay releases, releasing in turn slow releasing relay 2l3, which afteran interval longer than the release time of relay 208 connects ground238. During this open interval with relay 2558 released, relay 2 andalso relay 239, if this relay is again awaiting operation, now operate.Relay 2, however, disconnects conductor so that relay 252, and not relay2H! or operates. It thus appears that lines awaiting connection areserved by the sequence circuit sequentially in accordance with theirnumbered position in the sequence, and not in accordance with the orderof their call for service.

With relays 2 i0, 201 and 208 operated as before described, a circuit isclosed for operating relay 334, which circuit may be traced from batterythrough the winding of marginal relay 216, over conductor 2 ll, throughleft outer make contacts of relay 2%, left contacts of relay 2M, overconductor 233, right innermost contacts of relay HE), over conductor323, through contacts 324 of jack 309, over conductor 325, through leftand right windings of relay 334 to ground. Relay 334 operates, butmarginal relay 216, however, does not operate at this time. Relay 334 inoperating closes an obvious circuit through lamp 326, which is lightedindicating to the attendant that the circuit is now ready for theoperation of the position transfer key. To transfer to position 2, keyaid is accordingly operated. If key 3H! should be operated prematurely,that is, before lamp 326 is lighted, then a circuit is closed fromground, through right contact of key 3H3, back contacts of relay 334(which has not operated) to battery through lamp 321, which is lightedindicating that the circuits are not ready to effect the desiredtransfer, either because of failure to operate the transfer key M2, orthe non-availability of the sequence circuit at this moment.

In order to assist in differentiating clearly between the significanceof the two lamps, lamp 325 may be provided with a white, and lamp 327with a red cap. On operating key Sill, assuming that relay 334 isoperated, a circuit is closed from ground on its left contacts throughthe left contacts of key till, over' conductor 328 to the secondterminals of the hunting contact banks 2 35, 2GB and 2 Hi. .In thedrawings all brush arms are shown resting on the first contactterminals. It is to be understood, however, that the brush arms may restnormally on any contact terminal, since after a selection they remain onthe selected terminal. The operation of key 3H] with its right contactsconnects a ground to the right inner front contacts of relay 334,thereby short-circuiting the right or high resistance winding of relay334, which is connected to the said front contacts. Relay 33A continuesto hold through its winding. The resistance in the circuit of marginalrelay 2H3, is reduced and it now operates and closes a circuit fromground through the left back contacts of relay 2H1 and winding of slowreleasing relay 229 to battery. Relay 22E opcrates and closes a circuitfrom ground through its contacts 22land 222, back contacts of relay 223,right inner break contacts of relay 2!.9, over conductor 22%, rightinnermost contacts of relay 298, over conductor 225, right outermostcontacts of relay Hi3, over conductor 22% and through the selfinterrupting contacts and winding of rotary stepping magnet 2M tobattery. The brush arms 2% and 203 are now stepped around the contactbanks 206 and 2215 in the direction of the arrows respectively until thesecond terminal from the top isreached, which terminal is connected tothe grounded conductor 328. When this terminal is reached a circuit isclosed for operating relay 223 which is traced from battery through thewinding of relay 223, over conductor 22'l through the right outermostcontacts of relay 2%, brush arm 2%, second terminal of bank 295, overconductor 328, through left operated contacts of key 3? and relay 334 toground. Relay 223 in operating closes a circuit from ground throughcontacts 225 and 222 of relay 229, front contacts of relay 223, andwinding of relay 2l9 to battery. Relay 223 also opens the previouslytraced operating path of selector magnet 2i3i which stops the rotationof the brush arms leaving them on the second terminals, or contacts.Relay 2I9 operates and closes a circuit for holding itself and relay220, which is traced from battery through the winding of relay 220, leftfront contacts of relay 2I9, front contacts of relay 223, and contacts22I and 222 of relay 220 to ground. Relay 220 is slow in releasing andholds over the momentary open period while the left contacts of relayZI9 are operating. Relay 2I9 in operating also opens the operatingcircuit for magnet 20I, so that the subsequent release of relay 223 willnot again start the selector. Relay 2I9 in operating also closes acircuit from ground through contacts 2 2I of relay 220, right outercontacts of' relay 2I9, over conductor 228, right middle contacts ofrelay 208, over conductor 230 and through winding of relay H5 tobattery. 7

If, as a result of a previous selection, brush arms 202 and 203 had beenfound resting on the second terminals of I their associated banks, thenrelay 223 would have operated immediately and there would have been noswitch movement whatever. Relay H5 operates and locks through its leftinner contacts to ground on the right outer front contacts of sleeverelay I04, and with its right contacts opens the circuit of the windingof relay II 0, which releases. Relay II 0 in releasing, opens thecircuit of sequence relay 201 which releases, in return releasing relay208. The circuits of relays 2I6, 223 and 334, before traced, are nowopened and these relays release. The release of relay 223 releasesrelays 2I9 and 223. When relay 334 releases, the selector lamp 326 isextinguished and the disconnect lamp 321 is lighted, which indicates tothe attendant of position 1 that the transfer has been effected and thatkey 3I0 may now be released. The plug of the teletyepwriter cord circuit3I1should now be withdrawn from jack 300, which opens its uppermostcontacts releasing sleeve relay I04, which effects the operation ofrelay I I I in a circuit from battery through the winding of relay II I,left outer operated contacts of relay II 5 to ground on the right outerback contacts of relay I04. The locking circuit for relay H5, throughits left inner contacts is opened by the release of relay I04, but relayH5 is slightly slow in releasing so that relay II! has time to operatethe lock through its right contacts to the ground on conductor H8,before relay II 5 releases. Relay H1 in operating connects batterythrough its left inner contacts to conductor 3I6 thereby maintaining thelighting of the busy lamps at all positions, and with its left outercontacts connects battery to conductor 228, which is extendedover brusharm 202, second terminal of bank 204, con- .ductor 329 and through lamp304 to ground.

Lamp 304 is lighted and in response thereto the attendant at position 2inserts the plug of cord circuit 3H3 into jack 30I thereby connectingwith trunk H4 through the tip and sleeve conductors. When the uppermostcontacts of jack 30I connect ground to conductor 320, sleeve relay I04is operated again; removing ground from conductor H3 releasing relay III, which disconnects battery from conductor 229, thereby extinguishinglamp 394 at position 2. The operation of relay ice connects battery withits left innermost contacts to conductor 3I6, thereby maintaining thelighting of the busy lamps when relay I ll disconnects battery with itsleft inner contacts.

The hereinbefore given discussion described how an incoming call wasanswered at primary position 1 and was then transferred tosecondaryposition 2. In accordance with a feature of the invention, theattendant at position 2 may now retransfer the call, if required, to anyother position in the switchboard line up, in the same manner as wasdescribed for the transfer of the original call. If for instance atransfer to position 3 is required, transfer key 330 is operated andthen position key 33L After the operation of relay 332, ground isconnected to conductor 333, through the left operated contacts of key33f, grounding thereby the third terminal of bank 205. The invention nowfunctions as previously described in connection with the transfer of acall from position 1 to position, 2. Brush arms 202 and 203 stop on thethird terminal of banks 204, and 205, respectively. When 'the plug ofcord circuit (H8 is withdrawn from jack 30f, relay I04 releases andrelay II'I operates, lighting lamp 305 at position 3 over conductors 229and 3I4 through brush arm 202 and third terminal of bank 204.

The operation of the invention has been described for an incoming call.It may also be used for outgoing calls. The attendant at position 2, forinstance, may originate a call by plugging into jack 38!, therebyoperating sleeve relay I04 over Zonductor 326. Relay I04 in operatingconnects attery ductor 3ft, lighting the busy lamps at all positions.The attendant at the distant end of the line is signaled by theoperation of the break key of the teletypewriter or by opening thetelegraph key of cord circuit 3I8. If after communication has been thusestablished, it is desired to transfer the connection to anotherposition, this may be done in the same manner as described in connectionwith an incoming call.

The invention has been described using as a basis trunk I00, which isassociated with relays 2e? and 268, which are in the last position ofthe sequence circuit chain. The invention functions in a similar mannerfor trunks IOI and I02, which are in the second and first positions,respectively. Relay 209, however, does' not operate after its associatedrelay I I9 operates, unless relay 258 is normal at the time, so thatbattery 2I5 is available through the left inner contacts of relay 208over conductor 230. Similarly relay2 I I, does not operate immediately,when its associated relay I20 operates, unless relays 208 and 25d areboth not operated, thereby making battery 2E5 available through the leftinner contacts of relays 208 and 2| 0, over conductors 230 and 23LAlthough only three trunks are shown it is to be understood that othertrunks may be added. Additional pairs of sequence relays may beconnected in the same manner as are relays 209 and 2H0, 2H and 2I2. Theadditional relays should be connected to the vertical extensions ofconductors 232, 2H, 22?, 228 and 224 in which case battery 2I5 is alwaysassociated with the last relay in the sequence.

Figures 4, 5 and 6 Referring now to the arrangement of the inventionshown by Figs. 4, 5 and 6, 400 is an interofiice trunk which terminateson jacks 600, 60I and 652 of positions 1, 2 and 3, respectively.Associated with these jacks are answering lamps 693, 554 and 505 andbusy lamps 606, 601 and which calls may be answered by plugging into thewith its left innermost contacts to conjack associated with the lightedanswering lamp, or originated by plugging in and then operating theteletypewriter break key or holding the telegraph sending key openmomentarily. Additional jacks, answering and busy lamps may be providedat additional positions, not shown. As shown in the drawings, position 3is cross-connected by conductor 500, so that the associated answeringlamp 605 is lighted on an incomin call, that is, position 3 is a primaryanswering position. Position 2 is normally not thus connected, its lamp604 is lighted only on a transferred call, and is accordingly asecondary answering position. Position 1 may be either a primary orsecondary position. When the night key 609 of trunk 400, and all othersimilar night keys are operated, then position 1 is cross-connected sothat all incoming calls also effect the lighting of the line lamps ofposition 1, which is then a primary position. When key 609 and the othernight keys are not operated, then the cross-connections are noteffective, the answering lamps light only on transferred calls, andposition 1 is then a secondary position. By the proper cross-connectionany position in the switchboard line up may be arranged as either aprimary or answering position.

In order to transfer calls from one position to another, trunk 400 isprovided with a rotary type stepping switch, which is similar to thatshown in Fig. 2. Each terminal of bank 505 is connected to a conductorleading to an answering lamp at the respective positions, whereby eachlamp may be selectively lighted as required. Each contact of bank 506 isconnected to a conductor, to which ground is selectively connected byone of the positional transfer keys, such as key BID, 6H or B|2 ofposition 1. In effecting a transfer the position to which the call is tobe transferred is identified by the key M0, 6 or 612, etc., and thetrunk is identified by the associated transfer key, such as key 6H,which is an arrangement like that of Figs. 1, 2 and 3. In order to makeuse of a simple transfer trunk such as (H6, which is similar to thearrangement of Figs. 2 and 3; a sequence circuit is provided consistingof a pair of relays such as GM and 615, interconnected as shown for eachposition. With this arrangement, the transfer facilities of only oneposition are available at one time, thereby avoiding possibleinterference due to several attendants at different positions attemptingto transfer calls simultaneously. This arrangement differs from that ofFigs. 1, 2 and 3, since in the latter the sequence circuit wasassociated with the individual trunks and not with the positionaltransfer keys. Where there is a comparatively large number of trunkswith only a few switchboard positions the arrangement of Figs. 4, and 6may be more desirable than that of Figs. 1, 2 and 3, since fewersequence relays may be required. There is a possibility, however, thatin the arrangement of Figs. 1, 2 and 3 that the attendant at oneposition may attempt to transfer two trunks simultaneously. Adescription of the means whereby interference is avoided in this case isgiven hereinafter under Figs. 4, 5 and 6;

Figures 4, 5 and 6 A more complete understanding of the operation of thearrangement of Figs. 4, 5 and 6 may be obtained from the followingdiscussion which follows the progress of a call. Let it be assumed thatan attendant at a distant switchboard desires to communicate over line400 with the attendant at the secondary position 2. When the normallyclosed circuit of line 400 is momentarily opened relay 403 releases andcloses a circuit for operating relay 404, which is traced from batteryon the right back contacts of relay 405 through the winding of slowreleasing relay 434, closed break contacts of relay 4 03 to ground onthe right inner break contacts of sleeve relay 400. Relay 494 inoperating closes a circuit for operating relay 405, which is traced fromthe operating ground on the lower terminal of relay 40% through frontcontacts of relay 404 and winding of relay 405 to battery. After aninterval, relay 405 which is slow-to-operate, operates and opens withits right back contacts, the operating circuit for relay 404. It alsocloses with its left contacts a circuit from battery through the windingof relay G3? to the back contacts of relay 404. When this relay releasesafter an interval, if the contacts of relay 403 still remain closed, theoperating .ground on the winding of relay 404 operates relay 401, whichlooks over conductor 408 to ground on the right inn-er back contacts ofrelay 406. This arrangement of relays 403, 404, 405, and 401 isidentical with that of relays I03, I05, I06 and lii'i of Fig. l andfunctions in a similar manner. Relay 40'! in operating connects batterywith its right outer contacts to conductor 409, thence overcross-connection conductor 500 and conductor 623 to ground through lamp005, which is lighted, and with its middle right contacts connectsbattery over conductor 624 to the contacts of night key 609. When thiskey is operated, which is the case when position 1 is operated as anight position, then battery is extended also over conductor 625,cross-connection conductor 50L and conductor 026 to ground through lamp503 which lights.

Relay 107 also, with its right innermost contacts connects battery toconductor 628, thereby lighting busy lamps 606, 601 and 608. Theattendant at position 3, responds with the tele typewriter cord circuit622 and sleeve relay 4% operates over conductor 62? to ground throughthe uppermost local contacts of jack 602, and in operating removesground from conductor 08, releasing relay 407i and extinguishing lamp605. Relay 405 in operating connects battery with its left innermostcontacts to conductor 628, which maintains the lighting of the busylamps etc, 601

and 608, after battery has been removed by the release of relay 40?.Having been informed that the call should be transferred to position 2,the attendant at position 3 first operates the transfer key 629associated with jack G02 and thereby closes a circuit for operatingrelay 430 which is traced from battery through the winding of relay 4H3,over conductor 630, through contacts of key 829 to ground through theoperated contacts 63! of jack $02. The positional transfer key 650 isthen operated and a circuit is closed from battery 638 through thewinding of sequence circuit relay $32, lower back contacts of marginalrelay 633 to ground through the right contacts of key 630. Relay 632operates and if neither relay 5M or 034 is operated then a circuit isclosed from 1 battery through the winding of sequence relay 635, lowerfront contacts of relay e32, lower back contacts of relays 634 and 614,over conductor 636, through winding of relay 501 to ground on the breakcontacts of relay 508. Relays 535 and 50'! operate. Relay 501 inoperating closes an obvious circuit through the winding of slowreleasing relay 508 and locks to ground on its own contacts. Relay 508operates and disconnects the original operating ground. This arrangementof sequence relays operates in similar manner to that of Fig. 2discussed before in detail. Relay 635 in operating connects ground withits upper outer contacts to conductor 63?; thence this ground isconnected by the left operated contacts of key 630 to conductor 631,which terminates on the second terminal of hunting contact bank 506,thereby marking position 2 to receive the transferred call. Relay 635disconnects, with its upper inner break contacts, battery 638 fromconductor 639, thereby making this battery unavailable at this time forrelays 634 and 610. Relay 635 also closes a circuit which is traced fromground through the upper winding of marginal relay 633, upper operatedcontacts of relay 632, lower inner contacts of relay 535, over conductor640, and through the serially connected left and right windings of relay509 to battery. Relay 509 operates in this circuit, but marginal relay633 does not operate at this time. Relay 500 closes a circuit fromground through the left back contacts of relay 510 and winding of relay511 to battery. Relay 511 operates and closes a circuit which is tracedfrom battery through the left back contacts and right winding ofmarginal relay 512, operated left contacts of relay I, over conductor641, through lower outer operated contacts of relay 635, over conductor649 operated contacts 643 of jack 502, over conductor 644, through rightouter break contacts of relay 411, over conductor 513, through windingof marginal relay 514, over conductor 515 to ground on the right outeroperated make contacts of relay 410. Relay 510 operates but relay 512does not operate at this time. Relay 514 in operating closes a circuitfrom battery through winding and break contacts of stepping magnet 502,right outer contacts of relay 514, over conductor 516, right inner breakcontacts of relay 510, back contacts of relay 517, operated contacts 518and 519 of relay 5| 1, to ground on the break contacts of relay 512. Thebrush arms 503 and 504 are now rotated in the direction of the arrowsuntil contact 2 is reached. A circuit is then closed from batterythrough the winding of relay 51?, over conductor 520, through leftoperated contacts of relay 514, over conductor 521, brush arm 504,second contact of bank 506, over conductor 631, through left operatedcontacts of key 650 to ground on operated upper, outer contacts of relay635. Relay 51'1 operates and opens the operating circuit, hereinbeforetraced, of magnet 502, thereby causing brush arms 503 and 504 to stop onthe second terminals of banks 505 and 506. Relay 511 in operating closesa circuit for operating relay 510 which may be traced from batterythrough the Winding of relay 510, front contacts of relay.51'1, operatedcontacts 518 and 519 of relay 511 to ground on the break contacts ofrelay 512. Relay 510 looks with its left inner front contacts to groundon the contacts of relay 509, before relay 511, which is slow inreleasing, releases due to the opening of its circuit by the left backcontacts of relay 510. Relay 510 also closes a circuit from ground onthe contacts of relay 512, through contacts 518 and 519 of relay 51 1,also before this relay releases, right outer contacts of relay 510, overconductor 522, through right inner operated contacts of relay 514, overconductor 523 and left winding of relay 411 to battery. Relay 411operates and looks through its right winding and right inner contacts toground on the left outer operated contacts of relay 410, and with leftinner contacts connects battery to conductor 028 to maintain the busylamps lighted, when sleeve relay 400 subsequently releases ashereinafter described. Relay 4l1 also opens with its right outer breakcontacts the operating circuit for relay 514, which releases.

When relay 511 releases as hereinbefore described it connects batterythrough its right outer break contacts and the left operated outer makecontacts of relay 5l0 to the common terminal of the windings of relay509, which is equivalent to short circuiting the right winding of relay500. Relay 509, however, still holds through its left winding and, dueto the decreased resistance, marginal relay 633 now operates and closesan obvious circuit tobattery through the transfer lamp 613, whichlights. Relay 633 looks through its lower winding and front contacts toground on the right contacts of key 650 and also with its lower contactsopens the circuit of sequence relay 032, which releases and in turnreleases relay 635, thus immediately freeing the sequence circuit forthe use of attendants at other positions even though the attendant atposition 3 continues dilatorily to hold key 050 operated. Afterobserving the lighted lamp 613, the attendant releases key 650, whichreleases relay 633, extinguishing lamp 513. On withdrawing the plug ofcord circuit 622 from jack 602 sleeve relay 406 releases, releasingrelay 010. Relay 406 in releasing connects ground through its rightouter back contacts and through the right inner contacts and winding ofrelay 011 to battery. This prevents relay 311 from releasing when theground on the left outer contacts of relay 410 is disconnected. Relay406 in releasing also reconnects to the conductors of trunk 400, thewinding of line relay 403, which reoperates; The release of relay 410closes a circuit from battery through the right break contacts of relay410, left outer operated contacts of relay 411, over conductor 52 1,brush arm 503, second terminal of bank 505, over conductor 042 and toground through lamp 604, which lights. In response to the lighted lamp,the attendant at position 2, inserts the plug of cord circuit 021 intojack'601, and connects ground with the uppermost contacts of jack GM toconductor 021, thereby operating sleeve relay 405, which removes groundwith its right outermost back contacts from the right winding of relay411, which releases, extinguishing lamp 604. The busy lamps, at allpositions, however, are maintained operated, by battery connected toconductor 628, by the left innermost contacts of relay 005. If theattendant at position 2 should delay in answering, the attendant at thedistant office may recall the attendant at position 3 as in the case ofthe original call, relays 403, 004, 405 and 40'! functioning as beforeand effecting the lighting of lamp 605 at position 3. If the attendantat position 2 should find in communicating with the distant attendantthat the call should be transferred to some other position,

the transfer may be made in the manner hereinbefore described for theoriginal call. When the plug of the cord circuit 621 is withdrawn fromjack 601 relay 406 releases and the winding of relay 403 is reconnectedto trunk 400 Without opening the circuit, by means of the leftcontinuity springs of relay 406. Relay 403 reoperates and all apparatusis now ready for another call.

Another feature pertaining to the arrangement of Figs. 4, 5 and 6 willnow be discussed whereby the possibility of interference due to thesimultaneous transfer of calls from the same position is avoided. Let itbe assumed that a call over trunk 400 has been answered at position 3and that the trunk transfer key 629 has been operated all ashereinbefore described. If at this moment a call comes in over line 49!,associated lamp 653 lights and. the attendant may inadvertently insertthe plug of another cord circuit into jack 648 before completing thetransfer of the call on trunk toe. It may happen now that the attendantis requested to transfer the call on trunk 40!, and forgetting that thetransfer of the call on trunk 40!] has not been completed, may operatetransfer key 645, effecting the operation of relay 4 I 3 in the samemanner as the operation of relay M6 was previously effected. When apositional transfer key of position 3, key 550 for instance, is nowoperated, the circuit hereinbefore traced over conductor 649 nowbranches also through contacts 665 of jack 6 -38, over conductor 641,through outer right break contacts of relay 4I2, over conductor 525,through winding of relay 525, over conductor 52'! to ground on the rightouter operated contacts of relay 413. Marginal relay 5I2 now operates inthis circuit, but neither marginal relay 5M nor marginal relay 525operates. Relay 5l2 in operating opens with its left contacts the shortcircuit around its left winding thereby inserting the resistance of itsleft winding, and with its right contacts disconnects ground fromcontacts SIB and 5? of relay 5. Under this condition it is clear thatthe rotary switches controlled by magnets 582 and 528 do not operate.Marginal relay-533 does not operate and lamp M3 does not light. Thefailure of lamp M3 to light after key 638 has been held operated for aperiod of time more than is ordinarily sufiicient to effect a transfer,is an indication that a simultaneous double transfer has been improperlyattempted. The attendant will accordingly release key 650, causingrelays 632, 635, 509, 5 and EIZ to release. The attendant will alsoremove momentarily the cord circuit plug from one of the jacks, say jackE48, thereby releasing relay 4 I 3. When the attendant again operateskey 656 sequence relays 532 and 635 reoperate and the desired transferof the call on trunk 400 to position 2 is now effected, and lamp 6l3lights as hereinbefore described.

The preceding description has been based on the operation of trunk 498,with an incoming call answered at position 3 and transferred to position2. The operation with the other trunks 40! and 402 is similar, and atother positions the sequence circuit functions in like manner.

Figures 7, 8 and 9 Referring to the other arrangement of the inventiondisclosed by Figs '7, 8 and 9, the combination of Fig. '7 with Fig. 8will now be discussed. In Fig. '7 are shown three intercity telegraphiccommunication trunks 10D, Hit, and 192, which are arranged to cooperatewith a cross-bar switch CB which is of the same general construction asthat described in Patent No. 2,021,329, issued November 19, 1935 to J.N. Reynolds, from which patent a complete description may be obtained.The function of switch CB is to cooperate over transfer trunk 800 withpositional transfer keys shown in Fig. 8 in order to transfer calls tovarious positions in a telegraphic switchboard line up. The switch GB isshown with trunks 150, NH and 102 connected to cooperate with verticalsI, 2 and I0 respectively. Intervening verticals 3, 4, 5, 6, 1 and 8 areomitted as being unnecessary for the purpose of this description, andare symbolized by vertical 9 which is shown unconnected. Only fourhorizontals are shown, each of which represents positions respectively1, 2, 3 of Fig. 8, and position 4, not shown. Horizontals 5, 6, I, 8, 9and IE3 are not shown since these are not necessary in describing theinvention. By means of the switch CB ten trunks as 108, ml, i132, etc.may be served, and transferred to any one of ten positions. By using twoswitches any one of twenty trunks may be transferred to any one of tenpositions, or alternatively, any one of ten trunks may be transferred toany one of twenty positions. Furthermore, by using an N number ofcross-bar switches connected together horizontally there is providedspace for ten times N number of trunk circuits to ten positions; byusing M number of cross-bar switches connected together vertically thereis provided space for ten trunk circuits to ten times M positions; andby using N number of cross-bar switches connected together horizontallyand M number of cross-bar switches connected together vertically thereis provided by the joint arrangement ten times N number of trunkcircuits to ten times M number of positions, N and M being any desirednumbers.

When the attendant at the distant office originates a call on one of thetrunks, say trunk 199, by sending a long space signal, trunk N30 isgrounded and relays 183, NM and 7105 function so as to operate the lamp834 at position 1 of Fig. 8, assuming that the night key 8Ul is operatedso that this position is now a primary answering position. Also the lamp818 at position 3 is light-ed over conductor 892, and the busy lamps atall positions are lighted over conductor 8il3. This is in accordancewith the cross-connections Hi6 and The answering lamps for trunk IE0 atposition 1, when key SM is not operated and at position 2 are lightedonly on transferred calls. Any position may be cross-connected so as tofunction as either a primary or secondary position. In response to alighted answering lamp associated with trunk mil, the attendants pluginto the answering jacks 8B4, 895 or 8%, with the telegraph cordcircuits 801, 888 or 339, thereby extinguishing the lighted answeringlamps. In order to transfer a call from one position to another, aposition transfer key as key 868, 8| I, 812 or M3, corresponding to theposition to which the transfer is to be made, is operated. This causes astepping switch type of control circuit, shown at the bottom of Fig. 8,to function and to associate itself with the position from which thetransfer is to be made, provided the control circuit is not then in useat some other position. In operating, the control circuit causes aselecting magnet H38, 109, H0 or HI, corresponding to the position towhich the transfer is tobe made, to be energized and then also a holdingmagnet H2, H6 or H5, corresponding to the trunk 100, It! or 1% which isto be transferred. The contacts of switch CB, corresponding to theintersection of the operated holding and selecting magnet are nowclosed. When the transfer apparatus has completed its operation, asignal is given to the attendant by the lighting of the positionalrelease lamp Bill, 820 or 82!. The operated position key is thenreleased, and when the plug of the cord circuit, which was used toanswer the call, is withdrawn from the answering jack, the lamp at theposition to which the transfer is to be made is lighted. A more completeunderstanding of the operation of the arrangement of Figs. '7 and 8 maybe obtained by tracing the progress of a call as hereinafter described.

Let it be assumed that an attendant at a distant switchboard desires toinitiate a call over the trunk 99 for the attendant who is located atposition 2, which is accessible to trunk 10!! only as a secondaryanswering position. the conductor of trunk I08 is grounded due to thecalling impulse from the distant end a circuit is closed through theleft outer contacts of sleeve relay H5, winding of relay ms, to batteryon the left back contacts of relay Hi4. Relay H33 operates and closes acircuit through the winding of relay 16 2-, which is traced from batteryon the left operated contacts of relay 583, through the winding of relay"504 and the left outer contacts to the conductor of line m0. Relay l'lioperates and closes a locking circuit for itself from battery throughits left operated contacts and winding through the left break contactsof sleeve relay 7 Hi to the trunk conductor, and also with its left backcontacts opens the circuit of relay 703, which releases. Relay 103 inreleasing closes a circuit from battery through the winding of relay""25, right break contacts of relay N33 to ground on the right operatedcontacts of relay 164. Relay H14 is made slow-to-operate and relay Hi3slow-torelease, which arrangement necessitates that the calling signalbe maintained for an appreciable interval to assure the operation ofrelay 1G5 and accordingly safeguards the circuit against false signals,due to momentary line disturbances. When the calling pulse is terminatedrelay 1B4 releases. Relay 135 in operating locks through its right innercontacts to ground on the left inner contacts of sleeve relay H6; withits left outer front contacts it connects battery to conductor 1 il',thence through cross-connection it? to conductor 882, which extends toposition 3 at which the answering lamp 8I8 is lighted. Busy lamps 838,838, 832 and busy lamps at other positions, not shown, are all lightedover conductor 883 from battery on the right outer contacts of relay785. The attendant at position 3 responds by inserting the plug 853 ofthe telegraph cord circuit 899 into jack 8% and operating the lockingcord circuit key 825, which connects with its upper contacts theposition telegraph set 829 through the tip conductors of the plug 853and jack 8% to the conductor of trunk 166. A circuit is also closed.from battery through resistance 854, sleeve of plug 853 and jack 886,over conductor 833, through winding of relayiiii and right winding ofmarginal relay N93 to ground. Relay lit operates but relay He does notoperate at this time. Relay 1 i6 in operating removes the calling-insignal relays 1533 and 704 from the trunk lfiil with its left outercontacts, and with its left inner contacts opens the locking circuit ofrelay Hi5, which releases, extinguishing the lamp H8.

The attendant at position 3 is now in tele graphic communication withthe distant attendant. Should he be requested to transfer the call toposition 2, which is in accordance with the previous assumption he willaccordingly operate position transfer key 8! 2, which is'the key fortransferring calls to position 2, closing a circuit for operating startrelay 835, which is traced from battery through the winding of relay 835and the right contacts of key M2 to ground. Relay 835 in operatingcloses a circuit for operating the stepping magnet 836, which is tracedfrom battery through the winding of magnet 836 and its interruptingcontacts, left outer contacts of relay 837 to ground on the contacts ofrelay Key 8H? through its right contacts also connects ground toconductor 838, which extends to contact terminal No. 3 of hunting bank816, which terminal corresponds to position 3 at which the transfer isbeing effected. As indicated on the drawings other terminalscorresponding to other positions, are numbered consecutively in thedirection indicated by the arrow, which also indicates the direction ofrotation of the brush arm 839. 7

When the circuit through the winding of stepping magnet 83$ is closed asbefore described, brush arm 839 and the other brush arms of the switchare stepped around in the direction of the arrows until terminal No. 3is reached. Ground on terminal No. 3 is reached. Ground on terminal No.3 of hunting bank 8H3 connected as before described, now operates relay837, which opens with its left outer contacts the circuit of steppingmagnet 83$, thereby preventing the further movement of the switch. Acircuit is also closed for energizing selecting magnet 709 of the CBswitch, which is traced from battery through the winding of magnet 709,over conductor 840, through left operated contacts of key 8|2, overconductor 84!, through No. 3 contacts and brush arm 842 to ground on theleft inner contacts of relay 831. Relay 831 also closes a circuit foroperating relay 843, which is traced from battery on the right contactsof relay 837, through winding of relay 8&3 to ground on the left outercon tacts of relay 8%. Relay 53 in operating closes a circuit with itsmake contacts from battery on the right contacts of relay 831 to groundI through the winding of slow operating relay 844 which looks with itsleft inner contacts to battery on the right contacts of relay 837. Relay813 is designed to release slowly to assure that relay 844 locks upbefore its operating circuit 'is opened. Relay 8 is slow-to-operate toassure that relay 8 :3 operates and its magnetic circuit is saturatedbefore its operating circuit is opened and to assure a sufficient delayin energizing holding magnet H2, after selective magnet 'ifiQ isenergized, as will be hereinafter described.

When relay 85*! operates it closes a circuit from battery 845, throughresistance 846 and its right outer contacts, brush arm 84?, No. 3contact terminal of bank 8 i "5, over con-ductor 848, through loweroperated contacts of key 826, sleeve conductors of plug 853 and jack 8%,over conductor 833, through winding of sleeve relay H6 and right windingof marginal relay H9 to ground.

Battery 845 is of higher voltage than that of the I battery connected tosleeve resistance 854 and relay H9 now operates and looks from batterythrough its left contacts and winding to ground on the right outercontacts'of relay H6. Relay 159 with its right contacts connects groundover conductor l2ii through winding of selective magnet 7 82, overconductor 12! to battery on the left back contacts of relay Hi5, whichas before stated, released when relay H6 operated. Magnets H19 and H2are now both operated, operating springs 722, which are located at theintersection of the Vertical and horizontal corresponding respectivelyto magnets H2 and 789. Relay B44 operated also. closes a circuittraceable from battery on the right contacts of relay 831, through backcontacts of relay 843, right inner contacts of relay 844, brush arm 8 39and contact No. 3 of bank 8! to ground through release lamp 824, whichis lighted. The attendant at position 3 observing the lighted lamp 82Lknows that the selection has been completed and releases key 812 whichreleases magnet 109, making it immediately accessible to. the controlcircuit. Relays 835, 831 and 844 also release and the control circuit isnow ready for another selection at any position. Plug 853 is now removedfrom jack 806, which releases relays 116 and 119. Magnet 112 is held ina locking circuit through its left contacts which circuit is traced fromground on the right outer back contacts of relay over conductor 123 leftcontacts and winding of magnet 112, over conductor 121 and left backcontacts of relay 116 to battery. In order to maintain the circuit ofmagnet 112 continuously closed, ground is connected by the continuitycontacts of relay 116, to conductor 123, before the locking circuit ofrelay 119 is opened when relay 116 releases. When relay 116 releases,battery on the right inner contacts of relay 116 is disconnected fromconductor 803, but the battery on the left back contacts of relay isextended over conductor 121, through right contacts of magnet 112, toconductor 803, thereby maintaining the lighting of the busy lamps. Acircuit is also closed for lighting lamp 851 at position 2, which istraced from battery on the left back contacts of relay 119 overconductor 125, contacts 122 of switch CB over conductor 850 to groundthrough lamp 851.

The attendant at position 2 responds by inserting plug 852 of cordcircuit 808 into jack 805, thereby operating relay 116. Magnet 112releases due to the opening of its circuit at the right outer backcontacts of relay 116, and lamp 851 is extinguished.

If, after the lamp 851 is lighted, the attendant at position 2 shoulddelay his response the calling attendant may recall the attendant atposition 3, by reoperating relay 105 as hereinbefore described, therebyrelighting lamp 818.

In the description hereinbefore given position 3 was cross-connected asa primary, and position 2 as a secondary position. Position 1 isarranged regularly to operate as a secondary position, but when the key801 is operated it functions as a night position or primary position atwhich all incoming calls for the switchboard are answered, all otherpositions at this time being unattended. Key 801 is associated with alltrunks over conductor 822 and multiple conductor 126. When relay 105 isoperated, as before described, battery is connected, through thecontacts of key 801 over conductor 822, through left inner con tacts ofrelay 105, over conductor 118, cross-connection 106, conductor 823 andthrough lamp 834 to ground, which is lighted. The operator at position 1then answers by inserting plug 856 of cord circuit 801 into jack 804,the lamp 834 being extinguished by the operation of sleeve relay 119.Communication is established by operating cord circuit key 824.

Referring now to the alternative arrangement in which Fig. 7 cooperateswith Fig. 9, trunks 100, 101 and 102 are associated with jack and lampequipment in Fig. 9, identical with that of Fig. 8. Also, the cordcircuits at each position are the same as in Fig. 8. However, in Fig. 9,instead of a stepping switch type of control circuit a relay circuit,consisting of common relays 900, 901, 902 and positional relays 903, 904and 905 is used. When one of the positional transfer keys, as 906, 901,908 or 909 is operated, the associated positional control relay iscaused to operate, if the control circuit is not in use, and incooperation with the common relays of the control circuit effects theoperation of the apparatus of Fig. '7 over the conductors of thetransfer trunk 800 in the same manner as before described in connectionwith Fig. 8. A more complete understanding of this arrangement of theinvention may be obtained from the following detailed description.

Let it be assumed that a call over trunk 100 causes the apparatus ofFig. '7 to function as before described connecting battery to conductors802 and 803 and in this case causing the lighting of answering lamp 910and busy lamps 911, 912 and 913. The attendant at position 3 responds byinserting plug 914 of cord circuit 915 into jack 932. Lamp 910 isextinguished, and the busy lamps remain lighted, as before described.W'hen cord circuit key 916 is operated, communication over trunk 100 isestablished. Assuming now that the attendant of position 3 is requestedto transfer the call, as in the case of the arrangement of Figs. '7 and8, to position 2, position transfer key 908 is; accordingly operated,thereby closing a circuit from battery through the winding of relay 900,over conductor 918, through both windings of relay 905 in series toground on the right operated contacts of key 908. If now relay 903, 904,or some similar relay at another position, not shown is not operated,relay 905 operates. A discussion of the means whereby the controlcircuit functions so as to avoid interference, when a simultaneousattempt to transfer a call is made is discussed hereinafter. Relay 905with its upper inner contacts short circuits its high resistance upperwinding, which so reduces the resistance of the circuit that relay 900operates. Relay 905 continues to hold on its lower winding. Relay 900operated closes a circuit from ground on its left contacts, overconductor 919, through upper outer make contacts of relay 905, leftoperated contacts of key 908, over conductor 840 and to battery throughthe winding of selecting magnet 109, which operates. Another circuit isclosed from battery through the right contacts of relay 900, winding ofrelay 901 to ground on the left outer break contacts of relay 902. Relay901 operates and operates relay 902 in a circuit from ground through thewinding of relay 902, front contacts of relay 901 to battery on theoperated right contacts of relay 900, to which relay 902 looks throughits left inner contacts. Relay 902 releases slow release relay 901 andwith its outer right contacts connects battery 920 through resistance921 to conductor 922, through lower outer contacts of relay 905 toconductor 923. From conductor 923 battery 9201s extended through thelower operated contacts of cord circuit key 916 to the sleeve circuit ofplug 914 and jack 932. Battery 920 is of higher voltage than that of theregular sleeve circuit battery hence marginal relay 119 operates asbefore described in connection with Fig. 8 and energizes hold magnet112, closing contacts ,122. Another circuit is closed when relay 901eventually releases from battery on the right contacts of relay 900,break contact of relay 901 through right inner contacts of relay 902,over conductor 924, through lower inner contacts of relay 905 to groundthrough lamp 925, which is lighted, indicating to the attendant that theselection has been completed. Key 908 is now restored to normal whichreleases relays 900, 902 and 905 extinguishing lamp 925. Plug 914 is nowwithdrawn from jack 932 and lamp 926 at position 2 lights. The attendantat position 2 answers the call by inserting plug 921 of cord circuit 928into jack 929. and operating cord circuit key 93.0. From this point, thedescription in connection with Fig 7 and Fig. 8 applies.

The means whereby interference. is avoided, if attendants at diiferentpositions attempt to transfer calls simultaneously will now bediscussed. When key 908 was operated as before described it was assumedthat the common control circuit was not then in use. Suppose, however,that the circuit being used at position 2, that the associated relay 9%is operated and: the upper high resistance winding of relay 9% isshort-circuited and connected to ground through the operated rightcontacts of key 93L Under this condition the two serially connectedwindings of relay 905 are shunted by the low resistance lower winding ofrelay 9534- Relay 9&5 is marginal under this condition and does notoperate. Consequently position 2 encounters no interference fromposition 3. If key 898 should be operated simultaneously with key 93lrelays 95 i and 965 would then operate together. If each relay shouldclose its upper inner front contacts simultaneously and short-circuitits upper winding then the individ ual current flow through therespective lower windings of relays 9M and 905 would be so. small thatthe relays would immediately release. now one of the relays, say relay994, should re lease before relay 9125, then the low resistance shunt onthe winding of relay SE55 is removed and relay Q35 holds, and at thesame time shunts effectively the two serially connected windings ofrelay 904, which continues in' the released condition.

If the attendant at position 2, to which position the call answered atposition 3 was transferred, should be required to retransfer the call tosome other position, this may be done in the case of both Figs. 8 and 9in the same manner as in the case of an original call at a primaryposition.

The operation of the arrangement of Figs. '7, 8 and 9 has been discussedon the basis of calls incoming over trunks Hi0, ml and 582. Thisarrangement, however, is equally well adapted to handle outgoing cal-ls.

with the trunk over which the call is to be transmitted and operates thecord circuit key. By sending a spacing signal, i. e., grounding trunkfor a short period of time causes the signal rality of auxiliarycircuits connected in multiple.

to each of said switching devices and termina ing at said switchboard, aprimary signal lamp path and a plurality of secondary lamp pathsassociated to each of said auxiliary circuits and respectively having.appearances at different sections of said switchboard, a lamp in each ofsaid paths, a keyset at each section of said switchboard comprising keysfor initiating the transfer of an incoming call signal to a lamp in anydesired secondary lamp path, and switching means I associated with eachof said auxiliary circuits for automatically completing the transfer ofa call signal incoming over any one of said trunk circuits and appearingat one of the sections of said switchboard, to any one of the othersections of said switchboard.

To initiate a call an attendant plugs into the answering jack associated2. In amanually operated switchingsystem, a switchboard divided into aplurality of sections, a plurality of two-way trunk circuits terminatingin said switchboard, a plurality of auxiliary circuits associated withsaid trunk circuits terminating at each of said sections, a primarysignal lamp path and a plurality of secondary lamp paths associated witheach of said trunk circuits and respectively having appearances atdifferent sections, a lamp in each of said paths, a keyset at eachsection comprising keys for initiating the transfer of an incoming callsignal to a lamp in any desired secondary lamp path, switching meansassociated with each of said auxiliary circuits for automaticallycompleting the transfer of the incoming call signal appearing at onesection to any one of the other of said sections, and other auxiliarycircuits controlled by each of said keysets and each of said switchingmeans for transferring an incoming call signal transferred to asecondary signal lamp to any one other secondary lamps of said pluralityat any other of the other of said sections as desired.

3. In a manually operated switching system, according to claim 2,wherein the said lamp paths are provided with means for cross-connectingeach of said lamp paths to have either a primary lamp path appearance ora secondary signal lamp path appearance at any one of said. switchboardsections'as desired.

4. In a manually operated switching system, a switchboard divided into aplurality of primary sections'and into a plurality of secondarysections, a plurality of trunks for two-way messages, a switchingdevice, a plurality of circuits accessi ble to said device andrespectively terminating at the primary and secondary answering sectionsof said switchboard, indicators individual to certain of said circuitsrespectively appearing at said primary section, indicators individual tothe other of said circuits respectively appearing at said secondarysection, and means at each of said primary and at each of said secondarysections. for transferring a signal appearing on any one of saidindicators, primary or secondary, toany one of the secondary sections.

5. In a manually operated switching system, a switchboard divided into aplurality of primary sections and a plurality of secondary sections, aplurality of trunks for two-way messages, a rotary stepping switchindividual to each of said trunks, a plurality of auxiliary circuitsaccessible to each of said switches, primary trunk indicators individualto' certain of said auxiliary circuits and respectively appearing atsaid primary section, a secondary trunk indicators individual to theother of said auxiliary circuits and respectively appearin at saidsecondary section, means asociated with each trunk for selectivelyactuating the associated trunk indicator at any of said primary orsecondary sections, transferring meansassociated with each section forinitiating the transfer of a secondary or primary signal on any of saidindicators to any selected-section and for causing the functioning ofthe selecting means aforesaid, a transfer trunk common to all trunks andto all switchboard sections interconnecting said selecting means andsaid transferring means, and means whereby said transfer trunk iseffective for the transfer of only one signal at a time thereby avoidingcircuit interference.

6. In a manually operated switching system, a switchboard divided into aplurality of positions, a plurality of trunk circuits for incoming andoutgoing messages, a plurality of circuit paths comprising, a primarysignal lamp path and a plurality of secondary lamp paths accessible forconnection to each of said trunk circuits and respectively havingappearances at different positions, a lamp in each of said pathsconstituting an appearance, a key set at each of said positionscomprising keys for initiating the transfer of incoming call signals ona primary or a secondary signal lamp to any desired secondary signallamp, and a cross-bar switch common to each group of ten trunk circuitsarranged totransfer an incoming call signal transferred to a secondarysignal lamp to one of the other secondary signal lamps at any of theother of said positions as desired.

'1. In a manually operated switching system, a switchboard divided intoa plurality of primary positions and into a plurality of secondarypositions, a plurality of trunk circuits for two-way messages, a rotaryswitch terminating each trunk circuit, a plurality of circuit pathsaccessible to said switch and terminating in said switchboard at saidprimary and said secondary positions, primary trunk signals individualto certain of said circuit paths and respectively appearing at saidprimary positions, secondary trunk signals individual to certain otherof said circuit paths and respectively appearing at said secondarypositions, means associated with each trunk for selectively actuatingthe associated trunk signal at any one of said primary positions,transferring means associated with each position for initiating thetransfer of a primary trunk signal to any selected position and forcausing the functioning oi the selecting means aforesaid, a transfertrunk circuit common toall trunk circuits and to all switchboardpositions interconnecting said selecting means; and said transferringmeans, and means whereby said transfer trunk circuit is effective forthe transfer of only one signal at a time thereby avoiding interferencebetween trunk circuits.

ALLEN R. BONORDEN.

